Surface-protecting film and resin-sealed semiconductor device having said film

ABSTRACT

A surface-protecting film is formed on the surface of the semiconductor element of a resin-sealed semiconductor device to prevent the peeling and cracking of the sealing member used in said device, by coating on said surface a polyimide precursor composition containing a polyimide precursor having a recurring unit constitution represented by the following general formula (1) and heat-curing the coated polyimide precursor composition:                    
     wherein R 1  is a trivalent or tetravalent aromatic group; R 2  and R 3  are each a tetravalent organic group having 4 or more carbon atoms; R 4  is a bivalent organic group having 4 or more carbon atoms; X is a bivalent organic group containing at least one member selected from the group consisting of oxygen and nitrogen: Y is a monovalent organic group having 15 or less carbon atoms; n=5-100 and m=0-95 with a proviso that n+m=100; and p is 1 or 2).

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 08/517,613,filed on Aug. 22, 1995, now U.S. Pat. No. 6,087,006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device, a process forproduction thereof, and a surface-protecting film. More particularly,the present invention relates to a resin-sealed semiconductor deviceobtained by resin-sealing a semiconductor element whose surface iscoated with a polyimide, a process for production thereof, and asurface-protecting film suitable for protection of a semiconductorelement.

2. Description of the Related Art

In the conventional production of a resin-sealed semiconductor device,it is conducted, for the surface protection of semiconductor element orfor the prevention of semiconductor element malfunctioning caused by theα-ray emitted from sealing resin, to form a surface-protecting film of apolyimide resin on the surface of a semiconductor element and thenconduct sealing with a molding resin.

Mounting of such a resin-sealed semiconductor device is now conductedmainly by surface mounting. In the surface mounting, the leads ofsemiconductor device and the wires of printed wiring board aretemporarily connected, and the semiconductor device and the wiring boardare heated to conduct soldering. The heating is conducted mainly by amethod of using a radiant heat of infrared rays (infrared reflowing) ora method of using a condensation heat of fluorine-based inert fluid(vapor phase reflowing).

In such surface mounting, it occurs in some cases that the waterabsorbed inside a resin-sealed semiconductor device is rapidly vaporizedby the heat applied during soldering and the resulting vapor pressureallows the sealing member (resin) of said device to generate cracking.This cracking poses a serious problem with respect to the reliability ofsemiconductor device [Transactions of the Japan Society of MechanicalEngineers (A), 55 (510), 356-363 (1989)].

SUMMARY OF THE INVENTION

The first object of the present invention is to provide a semiconductordevice capable of preventing the cracking and peeling of the sealingmember during soldering. The second object of the present invention isto provide a process for producing such a semiconductor device. Thethird object of the present invention is to provide a surface-protectingfilm suitably used in such a semiconductor device.

According to the present invention, the peeling and cracking of sealingmember occurring during soldering can be prevented by the use of apolyimide film formed from a polyimide precursor having polarsubstituents as the side chains.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view showing a resin-sealed dynamic random accessmemory which is an example of the semiconductor device of the presentinvention.

FIGS. 2A to 2F are drawings showing an example of the process forproduction of semiconductor device, of the present invention.

FIG. 3 is a sectional view showing a resin-sealed discrete transistordevice which is an example of the semiconductor device of the presentinvention.

PREFERRED EMBODIMENTS OF THE INVENTION

In the present specification, when the recurring units of a polymer arerepresented by -A-, -B- and -C-, an expression of n -(A)-/m -(B)- refersto that the ratio of the recurring units -A- and -B- in the polymermolecule is n:m; and an expression of n -(A)-/m -(B)-/l -(C)- refers tothat the ratio of the recurring units -A-, -B- and -C- in the polymermolecule is n:m:l. The polymer may be a random copolymer or a blockcopolymer.

In order to achieve the above first object, there is provided, in thepresent invention, a resin-sealed semiconductor device comprising asemiconductor element having a surface-protecting film, externalterminals for electrical conduction with outside, and a sealing membercomprising a resin, in which semiconductor device the surface-protectingfilm comprises a polyimide obtained by heat-curing a polyimide precursorcomposition containing a polyimide precursor having a recurring unitconstitution represented by the following general formula (1)

(wherein R¹ is a trivalent or tetravalent aromatic group; R² and R³ areeach a tetravalent organic group having 4 or more carbon atoms; R⁴ is abivalent organic group having 4 or more carbon atoms; X is a bivalentorganic group containing at least one member selected from the groupconsisting of oxygen and nitrogen: Y is a monovalent organic grouphaving 15 or less carbon atoms; n=5-100 and m=0-95 with a proviso thatn+m=100; and p is 1 or 2). Incidentally, the semiconductor element maybe either of a semiconductor integrated circuit element and a discretetransistor element.

The polyimide film obtained by heat-curing a polyimide precursor havinga recurring unit constitution represented by the general formula (1) hasvery good adhesion to the sealing member (molding resin) of thesemiconductor device. Therefore, even when the water vapor pressureinside the polyimide film gets high during reflowing, the polyimide filmdoes not peel from the sealing member. Hence, in the presentsemiconductor device in which the semiconductor element has asurface-protecting film consisting of said polyimide film, there can beprevented cracking of the sealing member (molding resin) and peeling atthe interface between the sealing member and the surface-protectingpolyimide film.

Description is made on the semiconductor device of the presentinvention, with reference to an example of said device, i.e. aresin-sealed semiconductor device of lead-on-chip type (hereinafterabbreviated to LOC type) shown in FIG. 1. Incidentally, thesemiconductor device of the present invention is not restricted to a LOCtype alone and may be a resin-sealed semiconductor device of other typesuch as chip-on-lead type (hereinafter referred to as COL type) or thelike.

The resin-sealed semiconductor device of the present invention comprisesa semiconductor element 1 having a surface-protecting polyimide film 2on at least part of the surface; external terminals 3; an adhesivemember 4 bonding the semiconductor element 1 and the external terminals3 via the surface-protecting polyimide film 2; wires 5 electricallyconnecting the semiconductor element 1 and the external terminals 3; anda sealing member 6 completely sealing the semiconductor element 1 andthe wires 5. In the semiconductor device shown in FIG. 1, the externalterminals 3 function also as lead frames.

A discrete transistor device is shown in FIG. 3 as an example of theresin-sealed semiconductor device of COL type. This discrete transistordevice comprises a discrete transistor element 71 having asurface-protecting polyimide film 66; external terminals 70; lead frames65; an adhesive member 72; gold wires 67 electrically connecting thediscrete transistor element 71 and the external terminals 70; and asealing member completely sealing the element 71 and the wires 67. Thesurface-protecting polyimide film 66 is a polyimide film obtained byheat-curing a polyimide precursor composition containing a polyimideprecursor having a recurring unit constitution represented by the abovegeneral formula (1). The transistor element 71 consists of a siliconchip 61 functioning also as a collector; a base 62 and an emitter 63both formed in the chip 61; and a SiO₂ layer 64 formed on the side ofthe chip 61 in which the base 62 and the emitter 63 are formed. The SiO₂layer 64 has through- holes for formation of bonding pad areas, at theplaces corresponding to the electrodes of the base 62 and the emitter63; and each through-hole is filled with aluminum to form a conductorlayer 65 of bonding pad area. The surface-protecting film hasthrough-holes at the places corresponding to the bonding pad areas, andthe wires 67 connect the conductor layers 65 of bonding pad areas andthe external terminals 70.

In order to effectively prevent cracking of the sealing member 6 or 68,or peeling between the sealing member 6 or 68 and the surface-protectingfilm 2 or 66, it is necessary that at the interface between thesurface-protecting film 2 or 66 and the sealing member 6 or 68, thepolyimide (constituting the surface-protecting film 2 or 66) and themolding resin (constituting the sealing member 6 or 68) are chemicallybonded with each other or have a strong intermolecular action. Hence, inthe present invention, there was used, as the polyimide constituting thesurface-protecting film 2 or 66, a polyimide obtained by heat-curing acomposition containing a polyimide precursor having, as the side chains,polar substituents which can react with or have an interaction with themolding resin (e.g. an epoxy resin). By using such a polyimide, thesurface-protecting film 2 or 66 has very good adhesion to the sealingmember 6 or 68 and, even when water vapor generates inside thesemiconductor element during solder reflowing, there can be suppressedpeeling between the surface-protecting film 2 or 66 and the sealingmember 6 or 68, or cracking of the sealing member 6 or 68.

It is presumed that during the heat-curing of the polyimide precursorhaving a recurring unit constitution represented by the general formula(1), the side chain linkage X-Y of the polyimide precursor undergoesscission and, during the curing of the molding resin (e.g. an epoxyresin), the residual group of the X-Y linkage is chemically bonded withthe molding resin or comes to have a strong interaction with the polargroup of the molding resin.

The polyimide precursor composition may comprise a polyimide precursoralone, or a polyimide precursor and an appropriate solvent. Preferably,however, the composition comprises a polyimide precursor, an aminecompound having a carbon-to-carbon double bond and a photosensitizer,because such a composition has photosensitivity and can produce asurface-protecting film more easily. The amounts of the components inthe composition are desirably such that when the amount of the polyimideprecursor is 100 parts by weight, the amount of the amine compoundhaving a carbon-to-carbon double bond is 1-400 parts by weight and theamount of the photosensitizer is 0.1-30 parts by weight. Such amountproportions can allow the composition to have photosensitivity withoutimpairing the adhesion between the resulting polyimide film and thesealing member. Even with such a polyimide precursor compositioncontaining a polyimide precursor, a photosensitive amine compound and aphotosensitizer, the side chain linkage X-Y of the polyimide precursorundergoes scission during the heat-curing of the precursor and theresidual group is bonded with the molding resin, whereby strong adhesionbetween the surface-protecting film 2 or 66 and the sealing member 6 or68 is secured.

In order to achieve the above second object, there is provided, in thepresent invention, a process for producing a resin-sealed semiconductordevice, which comprises the following steps (i), (ii) and (iii) in thisorder:

(i) a protecting film formation step of forming, on at least part of thesurface of a semiconductor element, a surface-protecting polyimide filmby coating thereon a polyimide precursor composition containing apolyimide precursor having a recurring unit constitution represented bythe above general formula (1) and heat-curing the coated polyimideprecursor composition,

(ii) a semiconductor element-mounting step of mounting theabove-obtained semiconductor element having a protecting film, onexternal terminals, and

(iii) a sealing step of sealing the semiconductor element mounted onexternal terminals, with a molding resin.

The polyimide precursor composition used in the step (i) preferablycontains said polyimide precursor, an amine compound having acarbon-to-carbon double bond and a photosensitizer, because such acomposition has photosensitivity. The amounts of the components in thecomposition are desirably such that when the amount of the polyimideprecursor is 100 parts by weight, the amount of the amine compoundhaving a carbon-to-carbon double bond is 1-400 parts by weight and theamount of the photosensitizer is 0.1-30 parts by weight. Such amountproportions can allow the composition to have photosensitivity withoutimpairing the adhesion between the resulting polyimide film and thesealing member.

The surface-protecting film of semiconductor element must be formed onthe area of the front or back side of a semiconductor chip (a siliconwafer) other than the bonding pad areas allowing for electricalconduction with external terminals and the to-be-scribed regions atwhich the wafer is to be cut to separate each semiconductor element. Useof a polyimide precursor composition having photosensitivity permitsformation of a surface-protecting film in a pattern form by photoetchingand therefore is very suitable for formation of a surface-protectingfilm of semiconductor element.

Next, detailed description is made on the process for production ofsemiconductor device, of the present invention, with reference to FIGS.2A to 2F. While FIGS. 2A to 2F show a process for production of asemiconductor device of LOC type shown in FIG. 1, the present process isnot restricted only to said process for production of semiconductordevice of LOC type and can be applied also to a process for productionof other semiconductor device such as COL type or the like as long asthe device is obtained by bonding a semiconductor element and externalterminals (lead frames) and then conducting sealing with a moldingresin.

(i) Surface-protecting film formation step

As shown in FIG. 2A, a surface-protecting film 2 consisting of apolyimide is formed on one side of a silicon wafer 9 in which elementregions and wire layers have been formed. The surface-protecting film 2has a predetermined pattern, and the element 1 (see FIG. 2B) is exposedat the bonding pad areas 7 and the to-be-scribed regions 8. Theprotecting film of pattern shape is formed by various methods, forexample, (1) a method of coating a polyimide precursor composition onthe area of one side of the silicon wafer other than said areas 7 andsaid regions 8 and (2) a method of coating said composition on one sideof said silicon wafer, heat-curing the coated composition to form apolyimide film and removing, from the film, the portions correspondingto said areas 7 and said regions 8 by etching or the like.

The thus-obtained silicon wafer 9 having a surface-protecting film 2 iscut at the to-be-scribed regions to obtain each semiconductor element 1having a surface-protecting film 2, shown in FIG. 2B. In the above hasbeen described a method for obtaining a semiconductor element 1 having asurface-protecting film 2, by forming a surface-protecting film 2 on asilicon wafer 9 and cutting the wafer 9. Alternatively, thesemiconductor element 1 having a surface-protecting film 2 may beobtained by cutting a silicon wafer 9 to obtain a semiconductor element1, coating a polyimide precursor composition on the semiconductorelement 1, and heat-curing the coated composition.

(ii) Semiconductor element-mounting step

A polyamide imide ether layer is formed on one side of a polyimide filmto form an adhesive member 4. On the adhesive member 4 are providedexternal terminals 3, and beneath the adhesive member 4 is provided thesemiconductor element 1 having a surface-protecting film 2, obtained inthe step (i). They are press-bonded at 400° C. to obtain a materialshown in FIG. 2C, in which a semiconductor element 1 and externalterminals 3 are connected via a surface-protecting film 2 and anadhesive member 4. As shown in FIG. 2D, the bonding pad areas 7 of thesemiconductor element 1 and the external terminals 3 are connected withgold wires 5 by the use of a wire bonder to secure electrical connectionbetween the semiconductor element 1 and the external terminals 3.

(iii) Sealing step

As shown in FIG. 2E, the material obtained in the step (ii) is moldedwith a silica-containing epoxy resin at a molding temperature of 180° C.at a molding pressure of 70 kg/cm² to form a sealing member 6. Lastly,the external terminals 3 are bent in a predetermined shape to obtain aresin-sealed semiconductor device shown in FIG. 2F.

In the step (i) for formation of surface-protecting film, formation ofsurface-protecting film of pattern shape on the area of semiconductorelement other than the bonding pad areas 7 and the to-be-scribed regions8 can be conducted by the use of a photoetching method such as (1) a wetetching method using a photoresist and an etchant for polyimide and (2)a dry etching method of using an inorganic or metallic film of patternshape as a mask and removing the exposed polyimide film portion by theuse of an oxygen plasma.

When the polyimide precursor composition is endowed withphotosensitivity, the polyimide precursor composition is coated on thesemiconductor chip 9 and dried to form a dry film; the film isirradiated with ultraviolet rays or other radiation through a photomask;then, development is conducted to obtain a pattern of polyimideprecursor; the pattern is heat-cured; thereby, a polyimide pattern canbe obtained.

In order to achieve the above third object, there is provided, in thepresent invention, a surface-protecting film protecting the surface of asemi-conductor element, which is a polyimide film obtained byheat-curing a polyimide precursor composition containing a polyimideprecursor having a recurring unit constitution represented by the abovegeneral formula (1). The surface-protecting film of the presentinvention can also be used as an α-ray-shielding film.

The polyimide film obtained by heat-curing a polyimide precursor havinga recurring unit constitution represented by the general formula (1) hasvery good adhesion to sealing materials and moreover has excellent heatresistance and mechanical properties and therefore is suitable for thesurface protection of a semiconductor, particularly a semiconductor usedin resin-sealed semiconductor device.

Next, detailed description is made on the polyimide precursor having arecurring unit constitution represented by the general formula (1).

In the general formula (1) which is the recurring unit constitution ofthe polyimide precursor used in the present invention, R¹ is a trivalentor tetravalent aromatic group and may be two or more different groups,in view of the mechanical properties and heat resistance of thepolyimide film obtained. Specific examples of R¹ include groups havingthe chemical formulas (2) shown below, in view of the mechanicalproperties and heat resistance of the polyimide film obtained. R¹,however, is not restricted to these examples.

In the above, G is a group selected from the group consisting of thefollowing chemical formulas (3). —O—, —S—, —CO—, SO₂—, —CH₂—,

In the general formula (1), R² and R³ are each independently atetravalent organic group having 4 or more carbon atoms, in view of themechanical properties and heat resistance of the polyimide filmobtained. R² and R³ may be the same or different, and both or either ofR² and R³ may be two or more different groups. Specific examples of R²and R³ include groups having the chemical formulas (4) shown below, inview of the mechanical properties and heat resistance of the polyimidefilm obtained. R² and R³, however, are not restricted to these examples.

In the above, E is a group selected from the group consisting of thefollowing chemical formulas. —O—, —CO—, SO₂—, —CH₂—, —C(CH₃)₂—,

In the general formula (1), R⁴ is a bivalent organic group having 4 ormore carbon atoms and may be two or more different groups, in view ofthe mechanical properties and heat resistance of the polyimide filmobtained. Specific examples of R⁴ include groups having the followingchemical formulas (5), in view of the mechanical properties and heatresistance of the polyimide film obtained. R⁴, however, is notrestricted to these examples.

In the above, J is a group selected from the group consisting of thefollowing chemical formulas. —O—, —S—, SO₂—, —CO—, —CH₂—, —C(CH₃)₂—,—C(CF₃)₂—,

In the general formula (1), X is a bivalent group having at least onemember selected from the group consisting of oxygen and nitrogen.Specific examples of X, which are suitable in the present invention,include —COO—, —CONH—, —CO—, —NHCOO—, —NHCO—, —NHCONH—, —NH—, —NR⁵—, —O—and —CH₂O—. Of these groups, preferred are —COO—, —CO—, —NHCOO—, —NHCO—,—NHCONH—, —NH—, —NR⁵— and —CH₂O— and particularly preferred are —COO—,—NHCOO— and —NHCONH—, in view of the reactivity with molding resin (e.g.epoxy resin) and the easiness of scission of X-Y linkage duringheat-curing. R⁵ of —NR⁵— is an alkyl group of 5 or less carbon atoms,and specific examples thereof are —CH₃, —C₂H₅, —CH₂CH₂CH₃, —CH(CH₃)₂,—CH₂CH₂CH₂CH₃, —CH₂CH(CH₃)₂, —CH(CH₃)CH₂CH₃, —C(CH₃)₃ and—CH₂CH₂CH₂CH₂CH₃.

In the general formula (1), Y is a monovalent organic group having 15 orless carbon atoms and, in view of the easiness of synthesis, includesmonovalent organic groups having no carbon-to-carbon double bond, suchas —CH₃, —C₂H₅, —CH₂CH₂CH₃, —CH(CH₃)₂, —CH₂CH₂CH₂CH₃, —CH₂CH(CH₃)₂,—CH(CH₃)CH₂CH₃, —C(CH₃)₃, —CH₂CH₂OCOCH(CH₃)₂, —CH₂CH₂OCOC(CH₃)₃,—CH₂CH₂OCOCH₃, —CH₂CH₂OCOC₆H₅, —CH₂CH₂CH₂OCOC₆H₅, —CH₂CH₂OCH₃,—CH₂CH₂CH₂CH₂CH₃, —CH₂CH₂CH₂CH₂CH₂CH₃, —CH₂CH₂CH₂OCOC₆H₅,—CH₂CH₂CH₂OCH₃, —CH₂CH₂OCH₃, —CH₂CH₂CH₂OC₂H₅, —CH₂CH₂OC₂H₅,—CH₂CH₂CH₂OCH₂CH₂CH₃, —CH₂CH₂OCH₂CH₂CH₃, —CH₂CH₂CH₂OCH(CH₃)₂,—CH₂CH₂OCH(CH₃)₂, —CH₂CH₂CH₂OCH₂CH₂CH₂CH₃, —CH₂CH₂OCH₂CH₂CH₂CH₃,—CH₂CH₂CH₂OCH₂CH(CH₃)₂, —CH₂CH₂OCH₂CH(CH₃)₂, —CH₂CH₂CH₂OC(CH₃)₃,—CH₂CH₂OC(CH₃)₃, —CH₂CH₂CH₂OC₆H₅, —CH₂CH₂OC₆H₅ and the like. Of these,particularly preferred are —CH₂CH₂OCOCH(CH₃)₂, —CH₂CH₂OCOC(CH₃)₃ and—CH₂CH₂OCOCH₃ in view of the easiness of synthesis and the easiness ofscission between X and Y.

When R¹ is a trivalent aromatic group represented by the followingstructural formula (6), X is a bivalent organic group selected from—COO—, —NHCOO— and —NHCONH—, and Y is a monovalent organic grouprepresented by one of the following general formulas (7), the polyimideprecursor represented by the general formula (1) is, for example, acompound represented by the following general formula (8). The compoundof general formula (8) has excellent heat resistance and adhesion and issuitable for use in the present invention.

In the general formulas (7) and (8), k is an integer of 2-4. R⁶ is aphenyl group or an alkyl group of 4 or less carbon atoms in view of theeasiness of synthesis. Specific examples of R₆ are —CH₃, —C₂H₅,—CH₂CH₂CH₃, —CH(CH₃)₂, —CH₂CH₂CH₂CH₃, —CH₂CH(CH₃)₂, —CH(CH₃)CH₂CH₃,—C(CH₃)₃ and —C₆H₅. Of these groups, particularly preferred are —CH₃,—C₂H₅, —CH₂CH₂CH₃, —CH(CH₃)₂ and —C(CH₃)₃ because when R⁶ is such agroup, the compound of the general formula (1) is easy to synthesize andY of the (X-Y) linkage in the compound is easily eliminated from thelinkage by heat-curing, easily decomposed, and removed from the system.R² and R³ are each a tetravalent organic group having 4 or more carbonatoms; R⁴ is a bivalent organic group having 4 or more carbon atoms; Xis a bivalent organic group selected from —COO—, —NHCOO— and —NHCONH—;and n=5-100 and m=0-95 with a proviso that n+m=100.

Next, detailed description is made on the amine compound having acarbon-to-carbon double bond, used in the present invention. Said aminecompound can be a compound represented by the following general formula(9), but is not restricted thereto.

In the general formula (9), R⁷, R⁸ and R⁹ are each independently a groupselected from hydrogen, an alkyl group, a phenyl group, a vinyl groupand a propenyl group; R¹⁰ and R¹¹ are each independently a lower alkylgroup; and R¹² is a lower alkylene group.

Specific examples of the compound represented by the general formula (9)are 2-(N,N-dimethylamino)ethyl acrylate, 3-(N,N-dimethylamino)propylacrylate, 4-(N,N-dimethylamino)butyl acrylate,5-(N,N-dimethylamino)pentyl acrylate, 6-(N,N-dimethylamino)hexylacrylate, 2-(N,N-diethylamino)ethyl acrylate, 3-(N,N-diethylamino)propylacrylate, 4-(N,N-diethylamino)butyl acrylate, 5-(N,N-diethylamino)pentylacrylate, 6-(N,N-diethylamino)hexyl acrylate, 2-(N,N-dimethylamino)ethylmethacrylate, 2-(N,N-dimethylamino)propyl methacrylate,3-(N,N-dimethylamino)propyl methacrylate, 4-(N,N-dimethylamino)butylmethacrylate, 5-(N,N-dimethylamino)pentyl methacrylate,6-(N,N-dimethylamino)hexyl methacrylate, 2-(N,N-diethylamino)ethylmethacrylate, 3-(N,N-diethylamino)propyl methacrylate,4-(N,N-diethylamino)butyl methacrylate, 5-(N,N-diethylamino)pentylmethacrylate, 6-(N,N-diethylamino)hexyl methacrylate,2-(N,N-dimethylamino)ethyl sorbate, 3-(N,N-dimethylamino)propyl sorbate,4-(N,N-dimethylamino)butyl sorbate, 5-(N,N-dimethylamino)pentyl sorbate,6-(N,N-dimethylamino)hexyl sorbate, 2-(N,N-diethylamino)ethyl sorbate,3-(N,N-diethylamino)propyl sorbate, 4-(N,N-diethylamino)butyl sorbate,5-(N,N-diethylamino)pentyl sorbate, 6-(N,N-diethylamino)hexyl sorbate,2-(N,N-dimethylamino)ethyl cinnamate, 3-(N,N-dimethylamino)propylcinnamate, 4-(N,N-dimethylamino)butyl cinnamate,5-(N,N-dimethylamino)pentyl cinnamate, 6-(N,N-dimethylamino)hexylcinnamate, 2-(N,N-diethylamino)ethyl cinnamate,3-(N,N-diethylamino)propyl cinnamate, 4-(N,N-diethylamino)butylcinnamate, 5-(N,N-diethylamino)pentyl cinnamate and6-(N,N-diethylamino)hexyl cinnamate.

Of the above compounds, particularly preferred are2-(N,N-dimethylamino)ethyl methacrylate, 3-(N,N-dimethylamino)propylmethacrylate, 4-(N,N-dimethylamino)butyl methacrylate,5-(N,N-dimethylamino)pentyl methacrylate, 6-(N,N-dimethylamino)hexylmethacrylate, 2-(N,N-diethylamino)ethyl methacrylate,3-(N,N-diethylamino)propyl methacrylate, 4-(N,N-diethylamino)butylmethacrylate, 5-(N,N-diethylamino)pentyl methacrylate and6-(N,N-diethylamino)hexyl methacrylate, because they can impart goodphotosensitivity.

The amount used of the amine compound having a carbon-to-carbon doublebond is preferably 1-400 parts by weight, more preferably 10-200 partsby weight per 100 parts by weight of the polyimide precursor having arecurring unit constitution of the general formula (1). When the amountof the amine compound deviates from this range, the resultingphotosensitivity is insufficient and the developability or stability ofthe resulting film are affected adversely.

Detailed description is made on the photosensitizer used in the presentinvention. As the photosensitizer, there can be mentioned aphotosensitizing agent, a photopolymerization initiator, aphotosensitizing aid, a photopolymerization aid, etc. They can be usedsingly or in combination of two or more.

In the present invention, there can be used, as the photosensitizer,photosensitizing agents such as Michler's ketone,bis-4,4′-diethylaminobenzophenone, benzophenone,3,5-bis(diethylaminobenzylidene)-N-methyl-4-piperidone,3,5-bis(dimethylaminobenzylidene)-N-methyl-4-piperidone,3,5-bis(diethylaminobenzylidene)-N-ethyl-4-piperidone,3,3′-carbonylbis(7-diethylamino)coumarin, riboflavin tetrabutylate,2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one,2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone,3,5-dimethylthioxanthone, 3,5-diisopropylthioxanthone,1-phenyl-2-(ethoxycarbonyl)oxyiminopropan-1-one, benzoin ether, benzoinisopropyl ether, 1,9-benzanthrone, 5-nitroacenaphthene,5-nitro-1-acetonaphthone, 5-nitro-2-acetonaphthone, 2-nitrofluorene,anthrone, 1,2-benzanthraquinone, 1-phenyl-5-mercapto-1H-tetrazole,thioxanthen-9-one, 10-thioxanthenone, 3-acetylindole,2,6-di(p-dimethylaminobenzal)-4-carboxycyclohexanone,2,6-di(p-dimethylaminobenzal)-4-hydroxycyclohexanone,2,6-di(p-diethylaminobenzal)-4-carboxycyclohexanone,2,6-di(p-diethylaminobenzal)-4-hydroxycyclohexanone,4,6-dimethyl-7-ethylaminocoumarin, 7-diethylamino-4-methylcoumarin,7-diethylamino-3-(1-methylbenzimidazolyl)coumarin,3-(2-benzimidazolyl)-7-diethylaminocoumarin,3-(2-benzothiazolyl)-7-diethylaminocoumarin,2-(p-dimethylaminostyryl)benzoxazole,2-(p-dimethylaminostyryl)quionline, 4-(p-dimethylaminostyryl)quinoline,2-(p-dimethylaminostyryl)benzothiazole and2-(p-dimethylaminostyryl)-3,3-dimethyl-3H-indole. These compounds can beused singly or in combination of two or more.

Of the above compounds, preferred are Michler's ketone,bis-4,4′-diethylaminobenzophenone,3,5-bis(diethylaminobenzylidene)-N-methyl-4-piperidone,3,5-bis(dimethylaminobenzylidene)-N-methyl-4-piperidone,3,5-bis(diethylaminobenzylidene)-N-ethyl-4-piperidone,3,3′-carbonylbis(7-diethylamino)coumarin, riboflavin tetrabutylate,2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one,2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone,3,5-dimethylthioxanthone, 3,5-diisopropylthioxanthone,1-phenyl-2-(ethoxycarbonyl)oxyiminopropan-1-one, 5-nitroacenaphthene,2,6-di(p-dimethylaminobenzal)-4-carboxycyclohexanone,2,6-di(p-dimethylaminobenzal)-4-hydroxycyclohexanone,2,6-di(p-diethylaminobenzal)-4-carboxycyclohexanone,2,6-di(p-diethylaminobenzal)-4-hydroxycyclohexanone,4,6-dimethyl-7-ethylaminocoumarin, 7-diethylamino-4-methylcoumarin,7-diethylamino-3-(1-methylbenzimidazolyl)coumarin,3-(2-benzimidazolyl)-7-diethylaminocoumarin and3-(2-benzothiazolyl)-7-diethylaminocoumarin.

As the photosensitizer of the present invention, there can also be usedphotosensitizing aids such as 4-diethylaminoethyl benzoate,4-dimethylaminoethyl benzoate, 4-diethylaminopropyl benzoate,4-dimethylaminopropyl benzoate, 4-dimethylaminoisoamyl benzoate,N-phenylglycine, N-methyl-N-phenylglycine, N-(4-cyanophenyl)glycine,4-dimethylaminobenzonitrile, ethylene glycol dithioglycolate, ethyleneglycol di(3-mercaptopropionate), trimethylolpropane thioglycolate,trimethylolpropane tri(3-mercaptopropionate), pentaerythritholtetrathioglycolate, pentaerythrithol tetra(3-mercaptopropionate),trimethylolethane trithioglycolate, trimethylolpropane trithioglycolate,trimethylolethane tri(3-mercaptopropionate), dipentaerythritholhexa(3-mercaptopropionate), thioglycolic acid, α-mercaptopropionic acid,t-butyl peroxybenzoate, t-butyl peroxymethoxybenzoate, t-butylperoxynitrobenzoate, t-butyl peroxyethylbenzoate, phenylisopropylperoxybenzoate, di-t-butyl diperoxyisophthalate, tri-t-butyltriperoxytrimellitate, tri-t-butyl triperoxytrimesitate, tetra-t-butyltetraperoxypyromellitate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane,3,3′,4,4′-tetra(t-butylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(t-amylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(t-hexylperoxycarbonyl)benzophenone,2,6-di(p-azidobenzal)-4-hydroxycyclohexanone,2,6-di(p-azidobenzal)-4-carboxycyclohexanone,2,6-di(p-azidobenzal)-4-methoxycyclohexanone, 2,6-di(p-azidobenzal)-4-hydroxymethylcyclohexanone,3,5-di(p-azidobenzal)-1-methyl-4-piperidone,3,5-di(p-azidobenzal)-4-piperidone,3,5-di(p-azidobenzal)-N-acetyl-4-piperidone, 3,5-di(p-azidobenzal)-N-methoxycarbonyl-4-piperidone,2,6-di(p-azidobenzal)-4-hydroxycyclohexanone,2,6-di(m-azidobenzal)-4-carboxycyclohexanone,2,6-di(m-azidobenzal)-4-methoxycyclohexanone,2,6-di(m-azidobenzal)-4-hydroxymethylcyclohexanone,3,5-di(m-azidobenzal)-N-methyl-4-piperidone,3,5-di(m-azidobenzal)-4-piperidone,3,5-di(m-azidobenzal)-N-acetyl-4-piperidone,3,5-di(m-azidobenzal)-N-methoxycarbonyl-4-piperidone,2,6-di(p-azidocinnamylidene)-4-hydroxycyclohexanone,2,6-di(p-azidocinnamylidene)-4-carboxycyclohexanone,2,6-di(p-azidocinnamylidene)-4-hydroxymethylcyclohexanone,3,5-di(p-azidocinnamylidene)-N-methyl-4-piperidone,4,4′-diazidochalcone, 3,3′-diazidochalcone, 3,4′-diazidochalcone,4,3′-diazidochalcone, 1,3-diphenyl-1,2,3-propanetrione-2-(o-acetyl)oxime, 1,3-diphenyl-1,2,3-propanetrione-2- (-n-propylcarbonyl) oxime,1,3-diphenyl-1,2,3-propanetrione-2-(o-methoxycarbonyl) oxime,1,3-diphenyl-1,2,3-propanetrione-2-(o-ethoxycarbonyl) oxime,1,3-diphenyl-1,2,3-propanetrione-2-(o-benzoyl) oxime,1,3-diphenyl-1,2,3-propanetrione-2-(o-phenyloxycarbonyl) oxime,1,3-bis(p-methylphenyl)-1,2,3-propanetrione-2-(o-benzoyl) oxime,1,3-bis(p-methylphenyl)-1,2,3-propanetrione-2-(o-ethoxycarbonyl) oxime,1-(p-methoxyphenyl)-3-(p-nitrophenyl)-1,2,3-propanetrione-2-(o-phenyloxycarbonyl)oxime and the like. These compounds can be used singly or in combinationof two or more.

Of these photosensitizing aids, particularly preferred are4-diethylaminoethyl benzoate, 4-dimethylaminoethyl benzoate,4-dimethylaminoisoamyl benzoate, N-phenylglycine,N-methyl-N-phenylglycine, N-(4-cyanophenyl)glycine,4-dimethylaminobenzonitrile, pentaerythrithol tetrathioglycolate,pentaerythrithol tetra(3-mercaptopropionate), trimethylolethanetri-thioglycolate, trimethylolpropane trithioglycolate,trimethylolethane tri(3-mercaptopropionate), thioglycolic acid, t-butylperoxymethoxybenzoate, t-butyl peroxynitrobenzoate, t-butylperoxyethylbenzoate, phenylisopropyl peroxybenzoate, di-t-butyldiperoxyisophthalate, tri-t-butyl triperoxytrimellitate, tri-t-butyltriperoxytrimesitate, tetra-t-butyl tetraperoxy-pyromellitate,2,5-dimethyl-2,5-di(benzoylperoxy)hexane,3,3′,4,4′-tetra(t-butylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(t-amylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(t-hexylperoxycarbonyl)benzophenone and1,3-diphenyl-1,2,3-propanetrione-2-(o-ethoxycarbonyl) oxime.

As the photosensitizer of the present invention, there can also be usedphotopolymerization initiators such as acridine, nitropyrene,1,8-dinitropyrene, pyrene-1,6-quinone-9-fluorene, anthanthrone,2-chloro-1,2-benzanthraquinone, 2-bromobenzanthraquinone,3,5-diethylthioxanthone, benzil, 3-acetylphenanthrene, 1-indanone,7-H-benz[de]anthracene-7-one, 1-naphthaldehyde and the like. Thesecompounds can be used singly or in combination of two or more.

Of the above photosensitizers, preferred are 4-diethylaminoethylbenzoate, 4-dimethylaminoethyl benzoate, 4-dimethylaminoisoamylbenzoate, N-phenylglycine, N-methyl-N-phenylglycine,N-(4-cyanophenyl)glycine, 4-dimethylaminobenzonitrile, pentaerythritoltetrathioglycolate, pentaerythritol tetra(3-mercaptopropionate),trimethylolethane trithioglycolate, trimethylolpropane trithioglycolate,trimethylolethane tri(3-mercaptopropionate), thioglycolic acid, t-butylperoxymethoxybenzoate, t-butyl peroxynitrobenzoate, t-butylperoxyethylbenzoate, phenylisopropyl peroxybenzoate, di-t-butyldiperoxyisophthalate, tri-t-butyl triperoxytrimellitate, tri-t-butyltriperoxytrimesitate, tetra-t-butyl tetraperoxypyromellitate,2,5-dimethyl-2,5-di(benzoylperoxy)hexane,3,3′,4,4′-tetra(t-butylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra-t-amylperoxycarbonyl)benzophenone,3,3′,4,4′-tetra(t-hexylperoxycarbonyl)benzophenone and1,3-diphenyl-1,2,3-propanetrione-2-(o-ethoxycarbonyl) oxime.

The amount of the photosensitizer used is preferably 0.1-30 parts byweight, more preferably 0.3-20 parts by weight per 100 parts by weightof the polyimide precursor. When the amount deviates from the aboverange, no photosensitizing effect is obtained, or developability isaffected adversely.

The polyimide precursor composition used in the present invention maycontain a solvent in order to have a viscosity necessary for coating.The solvent is desirably an aprotic polar solvent in view of thesolvency. Specific examples of the solvent are N-methyl-2-pyrrolidone,N-acetyl-2-pyrrolidone, N-benzyl-2-pyrrolidone, N,N-dimethylformamide,N,N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphorictriamide, N-acetyl-ε-caprolactam, dimethylimidazolidinone, diethyleneglycol dimethyl ether, triethylene glycol dimethyl ether andγ-butyrolactone. These compounds may be used singly or in combination oftwo or more. In order to improve coatability, it is possible to add, tothe above solvent, an aromatic solvent such as toluene, xylene,methoxybenzene or the like as long as dissolution of polymer is notadversely affected by the addition.

In the present invention, coating of the polyimide precursor or thepolyimide precursor composition both of solution state can be conductedby various methods such as spin coating using a spinner, dipping, sprayprinting, screen printing and the like. The thickness of coating can becontrolled by the conditions of coating or the solid content insolution. After coating, drying is conducted to obtain a coating film ona silicon chip, after which heat-curing is conducted.

It is possible to form, from the photosensitivity imparted polyimideprecursor composition of the present invention, a film of pattern shapeby ordinary photolithography. That is, said polyimide precursorcomposition is coated on a semiconductor element and dried to form afilm on the semiconductor element; the film is irradiated withultraviolet rays through a photomask; the non-irradiated portion of thefilm is dissolved with a developer and removed; thereby, a desiredrelief pattern can be formed on the semiconductor element. The drying ofcoated composition is conducted desirably at a temperature selected fromthe range of 50-120° C. When the drying temperature is lower than 50°C., a long time is required for vaporization of solvent or dryingbecomes insufficient. When the drying temperature is higher than 120°C., a thermal reaction takes place and invites partial crosslinking anddevelopability of film is impaired.

As the developer, there can be used a good solvent for the compositionof the present invention, such as N-methyl-2-pyrrolidone,N-acetyl-2-pyrrolidone, N-benzyl-2-pyrrolidone, N,N-dimethylformamide,N,N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphorictriamide, N-acetyl-ε-caprolactam, dimethylimidazolidinone, diethyleneglycol dimethyl ether, triethylene glycol dimethyl ether,γ-butyrolactone or the like; or a mixture of the above good solvent anda non-solvent for the present composition, such as methanol, ethanol,isopropyl alcohol, toluene, xylene, 1,2-dimethoxyethane,2-methoxyethanol, 1-acetoxy-2-methoxyethane, water or the like.

The relief pattern formed by development is washed with a rinsingsolution to remove the developer. The rinsing solution has goodmiscibility with the developer, and preferred examples thereof aremethanol, ethanol, isopropyl alcohol, toluene, xylene,1,2-dimethoxyethane, 2-methoxyethanol, 1-acetoxy-2-methoxyethane andwater.

The thus-obtained polyimide precursor film is heated at a temperatureselected from the range of 200-450° C., whereby a polyimide havingexcellent heat resistance and physical properties is obtained. When theheating temperature is lower than 200° C., no imide ring formationreaction takes place, or the reaction is extremely slow. When thetemperature is higher than 450° C., the cured material causes thermaldecomposition. When a temperature higher than 300° C. is used, it isdesirable to conduct heating in an inert gas atmosphere such as N₂ orthe like.

Investigation by the present inventors on the cracking of sealing memberin conventional resin-sealed semiconductor device indicated that peelingoccurs at the interface between the protecting film (made of a polyimideresin) formed on semiconductor element and the sealing member (made of amolding resin) and this incurs cracking of the sealing member. Thereason therefor is presumed to be that the adhesion between thepolyimide resin and the molding resin is inferior.

In the present semiconductor device and the present process forproduction thereof, a polyimide film is formed with a polyimideprecursor having polar substituents as the side chains and this film hasimproved adhesion to the sealing resin of semiconductor device becausethe polar substituents have an interaction with the sealing resin. Owingto this improved adhesion, the present semiconductor device produced bythe present process is free from peeling between the protecting film onsemiconductor element and the sealing member, or from cracking of thesealing member.

The present invention is hereinafter described with reference toExamples. In the following Examples, viscosity was measured at 25° C. bythe use of a Brookfield type viscometer (DVR-E Model manufactured byTOKIMEC INC.).

SYNTHESIS EXAMPLE 1

There was synthesized a polyimide precursor having a recurring unitconstitution represented by the following chemical formula (10) (saidpolyimide precursor is hereinafter referred to as compound 1).

(1) Synthesis of diamine compound

2-(3,5-Diaminobenzoyloxy)ethyl isobutyrate (compound 4) was synthesizedin two stages according to the following reaction scheme (11).

83 g ((0.36 mol) of 3,5-dinitrobenzoyl chloride (compound 2) and 28 g(0.36 mol) of pyridine were placed in a 1-l four-necked flask equippedwith a dropping funnel, a reflux condenser, a thermometer and a mixingblade. Thereto was added 100 ml of dichloromethane for dissolution. Theflask was cooled to 10° C. with ice water. Thereto was dropwise added,in 20 minutes with the temperature (10° C.) being maintained, 62 g (0.47mol) of 2-hydroxyethyl 2-methylpropionate. After the dropwise addition,the flask was immersed in an oil bath of 50° C. and the flask contentswere stirred for 1 hour. The flask was cooled to room temperature and 50ml of water was added, followed by stirring for several minutes. All theflask contents were transferred into a separating funnel and the aqueouslayer was separated to remove. The organic layer taken out was returnedto the separating funnel. Thereto was added a 5% aqueous sodiumcarbonate solution, followed by mixing. The lower layer (organic layer)was taken out and dried over anhydrous magnesium sulfate. From the driedsolution was removed dichloromethane by distillation by the use of anevaporator, whereby a solid was separated. The solid was recrystallizedfrom a mixed solvent consisting of 200 ml of methanol and 100 ml ofwater to obtain 2-(3,5-dinitrobenzoyloxy)ethyl isobutyrate (compound 3).Yield: 100 g (86%) Melting point: 55-58° C.

9 g of 5% palladium carbon, 90 g (0.27 mol) of2-(3,5-dinitrobenzoyloxy)ethyl isobutyrate (compound 3) and 900 ml ofethanol were placed in a 5-l autoclave equipped with a thermocouplethermometer and a mixing blade, and the autoclave was sealed. Theatmosphere inside the autoclave was replaced by hydrogen and thehydrogen pressure was increased to 5 kg/cm². The autoclave contents werestirred at room temperature (7° C.). 10 minutes later, the autoclaveinside temperature rose to 34° C. and the autoclave inside pressuredropped to 1 kg/cm². Then, hydrogen was introduced to raise the pressureto 5 kg/cm², and stirring was continued. Ten minutes later, thetemperature became 50° C. and the pressure dropped to 1 kg/cm². Hydrogenwas again introduced to raise the pressure to 5 kg/cm², and stirring wascontinued. Since the temperature began to drop and the pressure becameconstant (4 kg/cm²), stirring was continued for 100 minutes (thetemperature dropped to 18° C.). The atmosphere inside the autoclave wasreplaced by nitrogen, and the autoclave contents were taken out andfiltered to remove palladium carbon. The filtrate was concentrated bythe use of an evaporator, whereby a solid was separated. The solid wasrecrystallized from 200 ml of toluene to obtain2-(3,5-diaminobenzoyloxy)ethyl isobutyrate (compound 4). Yield: 60 g(83%) Melting point: 81-83° C.

The structure of the compound 4 was confirmed by the infrared absorption(IR) spectrum and proton NMR (H¹-NMR) spectrum. The results are shown inTable 1.

TABLE 1 Characterization of diamine compounds No. of compound Name ofcompound

Melting point (° C.) Infrared absorption spectrum cm⁻¹ (KBr disc)

 4 2-(3′, 5′- —CH₂CH₂OCOCH(CH₃)₂ 81-83 3440 (—NH₂), 1.17(d, 6H, —CH₃),Diamino- 3360 (—NH₂), 2.58(m, 1H, —CH<), benzoyloxy)- 1735 (>C = 0),3.68 (br. s, 4H, —NH₂), ethyl 1705 (>C = 0) 4.38-4.41(m, 2H, —CH₂—),isobutyrate 4.45-4.48(m, 2H, —CH₂—), 6.20(t, 1H, aromatic), 6.77(d, 2H,aromatic) 17 2-(3′, 5′- —CH₂CH₂OCOCH₃ 76-77 3460 (—NH₂), 2.09(s, 3H,—CH₃), Diamino- 3370 (—NH₂), 3.68(br. s, 4H, —NH₂), benzoyloxy)- 1745(>C = 0), 4.37-4.40(m, 2H, —CH₂—), ethyl acetate 1730 (>C = 0)4.44-4.47(m, 2H, —CH₂—), 6.20(t, 1H, aromatic), 6.78(d, 2H, aromatic) 182-(3′, 5′- —CH₂CH₂OCOC(CH₃)₃ 73-75 3440 (—NH₂), 1.20(s, 9H, —CH₃),Diamino- 3370 (—NH₂), 3.68(br. s, 4H, —NH₂), benzoyloxy)- 1735 (>C = 0),4.37-4.39(m, 2H, —CH₂—), ethyl pivalate 1720 (>C = 0) 4.46-4.48(m, 2H,—CH₂—), 6.19(t, 1H, aromatic), 6.77(d, 2H, aromatic) 19 2-(3′, 5′-—CH₂CH₂OCOC₆H₅ 94-96 3460 (—NH₂), 3.34(br. s, 4H, —NH₂), Diamino- 3400(—NH₂), 4.56(m, 4H, —CH₂CH₂—), benzoyloxy)- 1730 (>C = 0) 6.23(t, 1H,aromatic), ethyl benzoate 6.63(d, 2H, aromatic), 7.53(m, 2H, aromatic),7.66(m, 1H, aromatic), 7.97(m, 1H, aromatic) 20 2-(3′, 5′-—CH₂CH₂CH₂OCOC₆H₅ 60-65 3420 (—NH₂), 3.37(br. s, 4H, —NH₂), Diamino-3325 (—NH₂), 4.40(m, 4H, —(CH₂)₃—), benzoyloxy)- 1725 (>C = 0) 6.22(t,1H, aromatic), propyl 6.63(d, 2H, aromatic), benzoate 7.53(m, 2H,aromatic), 7.66(m, 1H, aromatic), 7.97(m, 1H, aromatic)

(2) Synthesis of polyimide precursor

Using the above-obtained diamine (compound 4), there was synthesized apolyamic acid (a polyimide precursor) according to the followingreaction formula (12).

32.72 g of N-methyl-2-pyrrolidone (hereinafter abbreviated to NMP)dehydrated and dried with calcium hydride was placed as a solvent in a100-ml four-necked flask equipped with a thermometer and a mixing blade(motor-driven). Thereto were added 4.921 g (0.0185 mol) of the diamine(compound 4) and 0.2425 g (0.000976 mol) ofbis(3-aminopropyl)tetramethyldisiloxane (compound 5), followed bystirring for dissolution. To the resulting solution was added, in smallportions, 5.742 g (0.0195 mol) of powdery biphenyltetracarboxylic aciddianhydride (BPDA). During the addition, the liquid temperature rose to35° C.; one hour later, the temperature dropped to room temperature; 2hours later, BPDA dissolved completely. Then, stirring was conducted atroom temperature for 4 hours and the viscosity of the solution became3.10 Pa•s. The solution (solid content=25%) was filtered under pressurethrough a filter having pores of 5 μm to obtain an intended polyamicacid (compound 1).

SYNTHESIS EXAMPLE 2

There was synthesized a polyimide precursor having a recurring unitconstitution represented by the following chemical formula (13) (saidpolyimide precursor is hereinafter referred to as compound 6).

(1) Synthesis of diamine compound

2-(3,5-diaminophenylcarbamoyloxy)ethyl isobutyrate (compound 9) wassynthesized in two stages according to the following reaction scheme(14).

19.5 g (0.0822 mol) of 3,5-dinitrophenyl carbonyl azide was placed, in anitrogen current, in a 0.3-l four-necked flask equipped with a nitrogeninlet tube, a dropping funnel, a reflux condenser, a thermometer and amixing blade. Thereto was added acetonitrile for dissolution and thetotal amount was made 50 ml. The flask contents were heated forrefluxing to obtain 50 ml of an acetonitrile solution containing3,5-dinitrophenyl isocyanate (compound 7). While the flask was beingcooled with ice water, 12.0 g (0.0909 mol) of 2-hydroxyethyl2-methylpropionate was dropwise added to the flask contents withstirring. After the dropwise addition, stirring was conducted at roomtemperature for 2 hours; 50 ml of water was added; and stirring wasconducted for several minutes. Then, dichloromethane was added. All theflask contents were transferred into a separating funnel for separationof the aqueous layer. The organic layer taken out was returned to theseparating funnel. Thereto was added a 5% aqueous sodium carbonatesolution, followed by mixing. The lower layer (organic layer) was takenout and dried over anhydrous magnesium sulfate. From the dried solutionwas removed dichloromethane by distillation by the use of an evaporator,whereby a solid was separated. The solid was recrystallized from butanolto obtain 2-(3,5-dinitrophenylcarbamoyloxy)ethyl isobutyrate (compound8) as a yellow powder. Yield: 14.4 g (50%) Melting point: 94-95° C.

4.8 g of 5% palladium carbon, 48.0 g (0.141 mol) of2-(3,5-dinitrophenylcarbamoyloxy)ethyl isobutyrate (compound 8) and 700ml of ethanol were placed in a 5-l autoclave equipped with athermocouple thermometer and a mixing blade, and the autoclave wassealed. The atmosphere inside the autoclave was replaced by hydrogen andthe hydrogen pressure was raised to 5 kg/cm². The autoclave contentswere stirred at room temperature (20° C.). Ten minutes later, theautoclave inside temperature rose to 34° C. and the autoclave insidepressure dropped to 1 kg/cm². Then, hydrogen was introduced to raise thepressure to 5 kg/cm², and stirring was continued. 20 minutes later, thetemperature became 30° C. and the pressure dropped to 2.5 kg/cm².Hydrogen was again introduced to raise the pressure to 5 kg/cm², andstirring was continued. Since the temperature began to drop and thepressure became constant (3 kg/cm²), stirring was continued for 70minutes (the temperature dropped to 23° C.). The atmosphere inside theautoclave was replaced by nitrogen, and the autoclave contents weretaken out and filtered to remove palladium carbon. The filtrate wasconcentrated by the use of an evaporator. The resulting concentrate wasplaced under reduced pressure by the use of a rotary pump to distil offthe solvent to obtain 2-(3,5-diaminophenylcarbamoyloxy)ethyl isobutyrate(compound 9) as a brown viscous liquid. Yield: 33.7 g (85%)

The structure of the compound 9 was confirmed by the infrared absorption(IR) spectrum and proton NMR (H¹-NMR) spectrum. The results are shown inTable 2.

TABLE 2 Characterization of diamine compounds No. of compound Name ofcompound

Melting point (° C.) Infrared absorp- tion spectrum cm⁻¹

 9 2-(3, 5- —NHCOO(CH₂)₂OCOCH(CH₃)₂ oily 3420 1.17(d, 6H, —CH₃),diamino- (—NH₂), 2.58(m, 1H, —CH<), phenylcarba- 3330 3.58(s, 4H, —NH₂),moyloxy)- (—NH₂), 4.30(s, 4H, —CH₂CH₂—), ethyl 1710 5.73(s, 1H,aromatic), isobutyrate (>C = 0) 6.15(s, 2H, aromatic), 6.61(s, 1H, —NH—)13 2-(3,5- —NHCONH(CH₂)₂OCOCH(CH₃)₂ 89-90 3450 1.12(d, 6H, —CH₃),diamino- (—NH₂), 2.53(m, 1H, —CH<), phenyl- 3300 3.42(br. t, 2H, —CH₂—),ureido)ethyl (—NH₂), 4.10(t, 2H, —CH₂—), isobutyrate 1730 4.18(br. s,4H, —NH₂), (>C = 0) 5.66(s, 1H, aromatic), (KBr 5.90(s, 1H, —NH—), disc)6.13(s, 2H, aromatic), 7.52(s, 1H, —NH—)

(2) Synthesis of polyimide precursor

Using the above-obtained 2-(3,5-diaminophenylcarbamoyloxy)ethylisobutyrate (compound 9), there was synthesized a polyamic acid (apolyimide precursor) according to the following reaction formula (15).

32.8 g of NMP dehydrated and dried with calcium hydride was placed as asolvent in a 100-ml four-necked flask equipped with a thermometer and amixing blade (motor-driven). Thereto were added 5.181 g (0.0185 mol) ofthe diamine (compound 9) and 0.2425 g (0.000976 mol) ofbis(3-aminopropyl)tetramethyldisiloxane (compound 5), followed bystirring for dissolution. To the resulting solution was added, in smallportions, 5.742 g (0.0195 mol) of powdery BPDA. During the addition, theliquid temperature rose to 35° C.; one hour later, the temperaturedropped to room temperature; 2 hours later, BPDA dissolved completely.Then, stirring was conducted at room temperature for 4 hours and theviscosity of the solution became 3.10 Pa•s. The solution (solidcontent=25%) was filtered under pressure through a filter having poresof 5 μm to obtain an intended polyamic acid (compound 6).

SYNTHESIS EXAMPLE 3

There was synthesized a polyimide precursor having a recurring unitconstitution represented by the following chemical formula (16) (saidpolyimide precursor is hereinafter referred to as compound 10).

(1) Synthesis of diamine compound

There was synthesized 2-(3,5-diaminophenylureido)ethyl isobutyrate(compound 13) in three stages according to the following reaction scheme(17).

Acetonitrile was added to 19.5 g (0.0822 mol) of 3,5-dinitrophenylcarbonyl azide in a nitrogen current for dissolution and the totalvolume was made 50 ml. The resulting solution was heated for refluxingto obtain 50 ml of an acetonitrile solution containing 3,5-dinitrophenylisocyanate (compound 7).

11.0 g (0.180 mol) of 2-aminoethanol was placed, in a nitrogen current,in a 0.3-l four-necked flask equipped with a nitrogen inlet tube, adropping funnel, a reflux condenser, a thermometer and a mixing blade.Thereto was added 50 ml of acetonitrile, followed by stirring fordissolution. While the flask was being cooled with ice water, the flaskcontents were stirred. Thereto was dropwise added 50 ml of theabove-obtained acetonitrile solution containing 3,5-dinitrophenylisocyanate (compound 7). The mixture was stirred at room temperature for1 hour and then poured into 0.7 l of water. The separated crystals werecollected by suction filtration, washed with water and vacuum-dried at35° C. for 12 hours to obtainN-(3,5-dinitrophenyl)-N′-(2-hydroxyethyl)urea (compound 11) as a yellowpowder. Yield: 16.7 g (74%) Melting point: 192-194° C.

In a 0.3-l four-necked flask equipped with a dropping funnel, a refluxcondenser, a thermometer and a mixing blade were placed 18.0 g (0.0666mol) of N-(3,5-dinitrophenyl)-N′-(2-hydroxyethyl)urea (compound 11) and5.27 g (0.0666 mol) of pyridine. Thereto was added 150 ml ofdichloromethane. The mixture was stirred and became a yellow suspension.While the flask was being cooled with ice water, the flask contents werestirred. Thereto was dropwise added 8.52 g (0.0799 mol) of isobutyrylchloride. After the dropwise addition, the flask was immersed in an oilbath of 40° C. and the flask contents were stirred for 1 hour. Then, theflask contents were cooled to room temperature. Thereto was added 50 mlof water, and the mixture was stirred for several minutes. All the flaskcontents were transferred into a separating funnel for separation of theaqueous layer. The organic layer taken out was returned to theseparating funnel. Thereto was added a 5% aqueous sodium carbonatesolution, followed by mixing. The lower layer (organic layer) was takenout and dried over anhydrous magnesium sulfate. From the dried solutionwas removed dichloromethane by distillation by the use of an evaporator,whereby a solid was separated. The solid was recrystallized from a 2:1mixed solvent consisting of methanol and water to obtain2-(3,5-dinitrophenylureido)ethyl isobutyrate (compound 12) as a yellowpowder. Yield: 20.4 g (90%) Melting point: 89-92° C.

8.3 g of 5% palladium carbon, 83.0 g (0.244 mol) of2-(3,5-dinitrophenylureido)ethyl isobutyrate (compound 12) and 800 ml ofethanol were placed in a 5-l autoclave equipped with a thermocouplethermometer and a mixing blade, and the autoclave was sealed. Theatmosphere inside the autoclave was replaced by hydrogen and thehydrogen pressure was raised to 5 kg/cm². The autoclave contents werestirred at room temperature (17° C.). Ten minutes later, the autoclaveinside temperature rose to 43° C. and the autoclave inside pressuredropped to 1 kg/cm². Then, hydrogen was introduced to raise the pressureto 5 kg/cm², and stirring was continued. Ten minutes later, thetemperature became 58° C. and the pressure dropped to 1 kg/cm². Hydrogenwas again introduced to raise the pressure to 5 kg/cm², and stirring wascontinued. Since the temperature began to drop and the pressure becameconstant (4.5 kg/cm²), stirring was continued for 60 minutes (thetemperature dropped to 26° C.). The atmosphere inside the autoclave wasreplaced by nitrogen, and the autoclave contents were taken out andfiltered to remove palladium carbon. The filtrate was concentrated bythe use of an evaporator, whereby a solid was separated. The solid wasrecrystallized from 300 ml of butanol to obtain2-(3,5-diaminophenylureido)ethyl isobutyrate (compound 13). Yield: 55.0g (81%) Melting point: 89-90° C.

The structure of the diamine (compound 13) was confirmed by the infraredabsorption (IR) spectrum and proton NMR (H1-NMR) spectrum. The resultsare shown in Table 2.

(2) Synthesis of polyimide precursor

Using the above-obtained 2-(3,5-diaminophenylureido)ethyl isobutyrate(compound 13), a polyamic acid (a polyimide precursor) (compound 10) wassynthesized according to the following reaction formula (18).

34.38 g of NMP dehydrated and dried with calcium hydride was placed as asolvent in a 100-ml four-necked flask equipped with a thermometer and amixing blade (motor-driven). Thereto were added 5.476 g (0.0185 mol) ofthe diamine (compound 13) and 0.2425 g (0.000976 mol) ofbis(3-aminopropyl)tetramethyldisiloxane (compound 5), followed bystirring for dissolution. To the resulting solution was added, in smallportions, 5.742 g (0.0195 mol) of powdery BPDA. During the addition, theliquid temperature rose to 35° C.; one hour later, the temperaturedropped to room temperature; 2 hours later, BPDA dissolved completely.Then, stirring was conducted at room temperature for 4 hours and theviscosity of the solution became 3.10 Pa•s. The solution (solidcontent=25%) was filtered under pressure through a filter having poresof 5 μm to obtain an intended polyamic acid (compound 10).

SYNTHESIS EXAMPLES 4-7

There were synthesized four different polyimide precursors (hereinafterreferred to as compounds 14, 15, 16 and 17) having recurring unitconstitutions represented by the following chemical formulas (19), (20),(21) and (22), respectively.

(1) Synthesis of diamine compounds

By using a compound 2 and an appropriately selected ester and byemploying the same procedure as used for the synthesis of compound 4 inSynthesis Example 1, there were synthesized2-(3,5-diaminobenzoyloxy)ethyl acetate (compound 17),2-(3,5-diaminobenzoyloxy)ethyl t-butyrate (compound 18),2-(3,5-diaminobenzoyloxy)ethyl benzoate (compound 19) and2-(3,5-diaminobenzoyloxy)propyl benzoate (compound 20). The yield ofcompound 17 was 72% (yield of dinitro substance: 83%, yield of diamine:87%); the yield of compound 18 was 68% (yield of dinitro substance: 82%,yield of diamine: 83%); and the yield of compound 19 was 73% (yield ofdinitro substance: 86%, yield of diamine: 85%). The synthesis reactionsfor compounds 17-20 are shown in the following reaction schemes (23) and(24). The reaction scheme (23)(a) is for compound 17; the reactionscheme (23)(b) is for compound 18; the reaction scheme (24)(a) is forcompound 19; and the reaction scheme (24)(b) is for compound 20.

The structures of compounds 17-20 were confirmed by the infraredabsorption spectrum and proton NMR spectrum. The results are shown inTable 1.

(2) Synthesis of polyimide precursors

Each of the above-obtained diamines (compounds 17-20) was copolymerizedwith a compound 5 and biphenyltetracarboxylic acid dianhydride (BPDA) tosynthesize polyamic acids (polyimide precursors) (compounds 14, 15, 16-1and 16-2). The synthesis methods were the same as used for the synthesisof compound 1 (polyimide precursor) in Synthesis Example 1. The abovesyntheses were conducted according to the following reaction formulas(25) to (28). The reaction formula (25) is for compound 14; the reactionformula (26) is for compound 15; the reaction formula (27) is forcompound 16; and the reaction formula (28) is for compound 17.

SYNTHESIS EXAMPLES 8-21

Using diamine compounds synthesized in the same manners as in SynthesisExamples 1-7, there were synthesized various polyimide precursors(compounds 21-34) in the same manner as in the synthesis of thepolyimide precursor (compound 1) of Synthesis Example 1. The rawmaterials and their molar ratios used in Synthesis examples 8-21 areshown in Table 3.

TABLE 3 Raw materials and products of Synthesis Examples 8-21 Acid di-No. of anhydride Synthesis Diamine monomers monomer Examples (molarratio) (molar ratio) Product  8 Compound 4 Compound 5 m-PhenylenediamineBPDA Compound 21 (50) (5) (45) (100)  9 Compound 4 Compound 5m-Phenylenediamine BPDA Compound 22 (5) (5) (90) (100) 10 Compound 9Compound 5 m-Phenylenediamine BPDA Compound 23 (50) (5) (45) (100) 11Compound 9 Compound 5 m-Phenylenediamine BPDA Compound 24 (5) (5) (90)(100) 12 Compound 13 Compound 5 m-Phenylenediamine BPDA Compound 25 (50)(5) (45) (100) 13 Compound 13 Compound 5 m-Phenylenediamine BPDACompound 26 (5) (5) (90) (100) 14 Compound 17 Compound 5m-Phenylenediamine BPDA Compound 27 (50) (5) (45) (100) 15 Compound 17Compound 5 m-Phenylenediamine BPDA Compound 28 (5) (5) (90) (100) 16Compound 18 Compound 5 m-Phenylenediamine BPDA Compound 29 (50) (5) (45)(100) 17 Compound 18 Compound 5 m-Phenylenediamine BPDA Compound 30 (5)(5) (90) (100) 18 Compound 19 Compound 5 m-Phenylenediamine BPDACompound 31 (50) (5) (45) (100) 19 Compound 19 Compound 5m-Phenylenediamine BPDA Compound 32 (5) (5) (90) (100) 20 Compound 20Compound 5 m-Phenylenediamine BPDA Compound 33 (50) (5) (45) (100) 21Compound 20 Compound 5 m-Phenylenediamine BPDA Compound 34 (5) (5) (90)(100)

In Table 3, compound 21 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (29).

Compound 22 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (30).

Compound 23 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (31).

Compound 24 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (32).

Compound 25 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (33).

Compound 26 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (34).

Compound 27 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (35).

Compound 28 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (36).

Compound 29 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (37).

Compound 30 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (38).

Compound 31 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (39).

Compound 32 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (40).

Compound 33 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (41).

Compound 34 is a polyimide precursor having a recurring unitconstitution represented by the following structural formula (42).

SYNTHESIS EXAMPLE 22

There was synthesized a polyimide precursor having a recurring unitconstitution represented by the following chemical formula (43) (saidpolyimide precursor is hereinafter referred to as compound 35).

(1) Synthesis of diamine compound

2-(3,5-diaminophenylureido)ethyl isobutyrate (compound 13) wassynthesized in three stages according to the following reaction scheme(44).

Acetonitrile was added to 19.5 g (0.0822 mol) of 3,5-dinitrophenylcarbonyl azide in a nitrogen current for dissolution and the totalvolume was made 50 ml. The resulting solution was heated for refluxingto obtain 50 ml of an acetonitrile solution containing 3,5-dinitrophenylisocyanate (compound 7).

11.0 g (0.180 mol) of 2-aminoethanol was placed, in a nitrogen current,in a 0.3-l four-necked flask equipped with a nitrogen inlet tube, adropping funnel, a reflux condenser, a thermometer and a mixing blade.Thereto was added 50 ml of acetonitrile, followed by stirring fordissolution. While the flask was being cooled with ice water, the flaskcontents were stirred. Thereto was dropwise added 50 ml of theabove-obtained acetonitrile solution containing 3,5-dinitrophenylisocyanate (compound 7). The mixture was stirred at room temperature for1 hour and then poured into 0.7 l of water. The separated crystals werecollected by suction filtration, washed with water and vacuum-dried at35° C. for 12 hours to obtainN-(3,5-dinitrophenyl)-N-(2-hydroxyethyl)urea (compound 11) as a yellowpowder. Yield: 16.7 g (74%) Melting point: 192-194° C.

In a 0.3-l four-necked flask equipped with a dropping funnel, a refluxcondenser, a thermometer and a mixing blade were placed 18.0 g (0.0666mol) of N-(3,5-dinitrophenyl)-N-(2-hydroxyethyl)urea (compound 11) and5.27 g (0.0666 mol) of pyridine. Thereto was added 150 ml ofdichloromethane. The mixture was stirred and became a yellow suspension.While the flask was being cooled with ice water, the flask contents werestirred. Thereto was dropwise added 8.52 g (0.0799 mol) of isobutyrylchloride. After the dropwise addition, the flask was immersed in an oilbath of 40° C. and the flask contents were stirred for 1 hour. Then, theflask contents were cooled to room temperature. Thereto was added 50 mlof water, and the mixture was stirred for several minutes. All the flaskcontents were transferred into a separating funnel for separation of theaqueous layer. The organic layer taken out was returned to theseparating funnel. Thereto was added a 5% aqueous sodium carbonatesolution, followed by mixing. The lower layer (organic layer) was takenout and dried over anhydrous magnesium sulfate. From the dried solutionwas removed dichloromethane by distillation by the use of an evaporator,whereby a solid was separated. The solid was recrystallized from a 2:1mixed solvent consisting of methanol and water to obtain2-(3,5-dinitrophenylureido)ethyl isobutyrate (compound 12) as a yellowpowder. Yield: 20.4 g (90%) Melting point: 89-92° C.

8.3 g of 5% palladium carbon, 83.0 g (0.244 mol) of2-(3,5-dinitrophenylureido)ethyl isobutyrate (compound 12) and 800 ml ofethanol were placed in a 5-l autoclave equipped with a thermocouplethermometer and a mixing blade, and the autoclave was sealed. Theatmosphere inside the autoclave was replaced by hydrogen and thehydrogen pressure was raised to 5 kg/cm². The autoclave contents werestirred at room temperature (17° C.). 10 minutes later, the autoclaveinside temperature rose to 43° C. and the autoclave inside pressuredropped to 1 kg/cm². Then, hydrogen was introduced to raise the pressureto 5 kg/cm², and stirring was continued. 10 minutes later, thetemperature became 58° C. and the pressure dropped to 1 kg/cm². Hydrogenwas again introduced to raise the pressure to 5 kg/cm², and stirring wascontinued. Since the temperature began to drop and the pressure becameconstant (4.5 kg/cm²), stirring was continued for 60 minutes (thetemperature dropped to 26° C.). The atmosphere inside the autoclave wasreplaced by nitrogen, and the autoclave contents were taken out andfiltered to remove palladium carbon. The filtrate was concentrated bythe use of an evaporator, whereby a solid was separated. The solid wasrecrystallized from 300 ml of butanol to obtain2-(3,5-diaminophenylureido)ethyl isobutyrate (compound 13). Yield: 55.0g (81%) Melting point: 89-90° C.

The structure of the diamine (compound 13) was confirmed by the infraredabsorption spectrum and proton NMR spectrum. The results are shown inTable 4.

TABLE 4 Name of compound 2-(3,5-diaminophenylureido)ethyl isobutyrateStructure

Melting point (° C.) 89-90 Infrared absorption 3450 (—NH₂), 3300 (—NH₂)1730 (>C = 0) spectrum cm⁻¹ (KBr disc) Nuclear magnetic 1.12(d, 6H,—CH₃), 2.5(m, 1H, —CH<), 3.42(br. resonance spectrum t, 2H, —CH₂—),4.10(t, 2H, —CH₂—), 4.18(br. s, δ (H¹-NMR) 4H, —NH₂), 5.66(s, 1H,aromatic), 5.90(s, 1H, (Solvent(CD₃)₂CO) —NH—), 6.13(s, 2H, aromatic),7.52(s, 1H, —NH—)

(2) Synthesis of polyimide precursor

Using 2-(3,5-diaminophenylureido)ethyl isobutyrate (compound 13), apolyamic acid (a polyimide precursor) (compound 35) was synthesizedaccording to the following reaction formula (45).

32.8 g of N-methyl-2-pyrrolidone (hereinafter abbreviated to NMP)dehydrated and dried with calcium hydride was placed as a solvent in a100-ml four-necked flask equipped with a thermometer and a mixing blade(motor-driven). Thereto were added 5.181 g (0.0185 mol) ofN-(3,5-diaminophenyl)-N-(2-isopropoxycarbonylethyl)urea (compound 13)and 0.2425 g (0.000976 mol) of bis(3-aminopropyl)tetramethyldisiloxane(compound 5), followed by stirring for dissolution. To the resultingsolution was added, in small portions, 5.742 g (0.0195 mol) of powderybiphenyltetracarboxylic acid dianhydride (BPDA). During the addition,the liquid temperature rose to 35° C.; one hour later, the temperaturedropped to room temperature; 2 hours later, BPDA dissolved completely.Then, stirring was conducted at room temperature for 4 hours and theviscosity of the solution became 3.10 Pa•s. The solution (solidcontent=25%) was filtered under pressure through a filter having poresof 5 μm to obtain an intended polyamic acid (compound 35).

EXAMPLES 1-3 AND COMPARATIVE EXAMPLES 1-2

Various polyimide precursors each composed of2-(3,5-diaminophenylureido)ethyl isobutyrate (compound 13),bis(3-aminopropyl)tetramethyldisiloxane (compound 5) andm-phenylenediamine were synthesized in the same manner as in SynthesisExample 1 by changing the proportions of these three components, inorder to investigate the amount of compound 13 required in polyimideprecursor in order for the polyimide formed from said polyimideprecursor to show sufficient adhesion to a sealing resin forsemiconductor device. As in Synthesis Example 1, these polyimideprecursors were each obtained in a polyimide precursor composition ofsolution form (solid content=25%).

Each polyimide precursor was spin-coated on a silicon wafer in whichsemiconductor element regions and wiring layers had been formed. Thecoated composition was dried at 90° C. for 4 minutes and then at 100° C.for 4 minutes to obtain a film having a thickness of 18 μm. Each filmwas cured at 200° C. for 30 minutes and then at 350° C. for 30 minutesto obtain a polyimide film having a thickness of 10 μm. Each polyimidefilm was subjected to photoetching using a cyclized polyisoprene-basedphotoresist and a hydrazine-based etchant for polyimide, to remove theportions of the polyimide film corresponding to the bonding pad areasand to-be-scribed regions of the silicon wafer. Then, the remainingphotoresist was removed to obtain each wafer having a polyimide film (asurface-protecting film) at the surface portions other than the bondingpad areas and to-be-scribed regions.

Each wafer obtained above was cut at the to-be-scribed regions toseparate individual chips. On the surface of the chip was press-bonded,at 400° C., external terminals supported on a polyimide film having alower layer of a polyamide imide ether adhesive. Then, the bonding padareas of the chip and the external terminals were connected with a goldwire by the use of a wire bonder. Thereafter, molding was conducted bythe use of a silica-containing epoxy sealant at a temperature of 180° C.at a pressure of 70 kg/cm² to form a resin-made sealing member. Lastly,the external terminals were bent in a desired shape to obtain a productof DRAM (dynamic random access memory).

Each DRAM was kept for 200 hours in an atmosphere of 85° C.(temperature) and 85% (relative humidity), then heated at 260° C. for 10seconds (solder reflowing conditions), and subjected to ultrasonicsearch to examine the occurrence or non-occurrence of peeling. Peelingseen on whole surface was rated as “whole-surface peeling”; partialpeeling at one or more of four corners was rated as “partial peeling”;and no peeling was rated as “no peeling”. In order to examine the heatresistance of polyimide, a polyimide film having a thickness of 10 μmwas prepared separately and measured for weight decrease-startingtemperature. Incidentally, weight decrease-starting temperature wasrated as “good” when the temperature was 380° C. or more, because apolyimide film having a weight decrease-starting temperature of 380° C.or more can be put into practical application. The proportions of rawmaterials and evaluation results of products in each Example andComparative Example are shown in Table 5.

TABLE 5 Compositions of polyamic acids and evaluations of polyimidesproduced therefrom Heat Acid dianhydride Peeling resist- Diaminemonomers (molar ratio) (molar ratio) resistance ance Example 1 2-(3,5-m- Bis(3-amino- 3,3′,4,4′- No peeling Good diaminophenyl- Phenylene-propyl)- Biphenyltetracarbo- ureido)ethyl diamine tetramethyl- xylicacid isobutyrate (55) disiloxane dianhydride (40) (5) (100) Example 22-(3,5- m- Bis(3-amino- 3,3′,4,4′- No peeling Good diaminophenyl-Phenylene- propyl)- Biphenyltetracarbo- ureido)ethyl diaminetetramethyl- xylic acid isobutyrate (75) disiloxane dianhydride (20) (5)(100) Example 3 2-(3,5- m- Bis(3-amino- 3,3′,4,4′- No peeling Gooddiaminophenyl- Phenylene- propyl)- Biphenyltetracarbo- ureido)ethyldiamine tetramethyl- xylic acid isobutyrate (90) disiloxane dianhydride(5) (5) (100) Comparative 2-(3,5- m- Bis(3-amino- 3,3′,4,4′- PartialGood Example 1 diaminophenyl- Phenylene- propyl)- Biphenyltetracarbo-peeling ureido)ethyl diamine tetramethyl- xylic acid isobutyrate (92)disiloxane dianhydride (3) (5) (100) Comparative 2-(3,5- m- Bis(3-amino-3,3′,4,4′- Whole- Good Example 2 diaminophenyl- Phenylene- propyl)-Biphenyltetracarbo- surface ureido)ethyl diamine tetramethyl- xylic acidpeeling isobutyrate (95) disiloxane dianhydride (0) (5) (100)

As is clear from the results shown in Table 5, compound 13 was certainlyeffective for adhesion between polyimide film and molding resin. Goodheat resistance was obtained in all cases. However, in order to obtaingood adhesion, compound 13 must be used, in copolymerization, in anamount of 5 mole % or more based on the total amount of diamines.

EXAMPLES 4-6 AND COMPARATIVE EXAMPLES 3-4

Next, investigation was made on a case using2-(3,5-diaminophenylcarbamoyloxy)ethyl isobutyrate (compound 9) as adiamine monomer. In Examples 4-6 and Comparative Examples 3-4,2-(3,5-diaminophenylcarbamoyloxy)ethyl isobutyrate (compound 9) was usedin place of the 2-(3,5-diaminophenylureido)ethyl isobutyrate (compound13) used in Examples 1-3 and Comparative Examples 1-2; and peeling andheat resistance were evaluated in the same manner as in Examples 1-3 ndComparative Examples 1-2. The proportions of raw materials andevaluation results of products in each Example and Comparative Exampleare shown in Table 6.

TABLE 6 Compositions of polyamic acids and evaluations of polyimidesproduced therefrom Heat Acid dianhydride Peeling resist- Diaminemonomers (molar ratio) (molar ratio) resistance ance Example 4 2-(3,5-m- Bis(3-amino- 3,3′,4,4′- No peeling Good diaminophenyl- Phenylene-propyl)- Biphenyltetracarbo- carbamoyloxy) diamine tetramethyl- xylicacid ethyl (55) disiloxane dianhydride isobutyrate (5) (100) (40)Example 5 2-(3,5- m- Bis(3-amino- 3,3′,4,4′- No peeling Gooddiaminophenyl- Phenylene- propyl)- Biphenyltetracarbo- carbamoyloxy)diamine tetramethyl- xylic acid ethyl (75) disiloxane dianhydrideisobutyrate (5) (100) (20) Example 6 2-(3,5- m- Bis(3-amino- 3,3′,4,4′-No peeling Good diaminophenyl- Phenylene- propyl)- Biphenyltetracarbo-carbamoyloxy) diamine tetramethyl- xylic acid ethyl (90) disiloxanedianhydride isobutyrate (5) (100) (5) Comparative 2-(3,5- m-Bis(3-amino- 3,3′,4,4′- Partial Good Example 3 diaminophenyl- Phenylene-propyl)- Biphenyltetracarbo- peeling carbamoyloxy) diamine tetramethyl-xylic acid ethyl (92) disiloxane dianhydride isobutyrate (5) (100) (3)Comparative 2-(3,5- m- Bis(3-amino- 3,3′,4,4′- Whole- Good Example 4diaminophenyl- Phenylene- propyl)- Biphenyltetracarbo- surfacecarbamoyloxy) diamine tetramethyl- xylic acid peeling ethyl (95)disiloxane dianhydride isobutyrate (5) (100) (0)

As is clear from the results shown in Table 6, compound 9 was certainlyeffective for adhesion between polyimide film and molding resin. Goodheat resistance was obtained in all cases. However, in order to obtaingood adhesion, compound 9 must be used, in copolymerization, in anamount of 5 mole % or more based on the total amount of diamines.

EXAMPLE 7

Using compound 1 [a polyimide precursor having a recurring unitconstitution represented by chemical formula (10)], a semiconductordevice shown in FIG. 1 (a DRAM in the present Example) was produced andexamined for the adhesion between the surface-protecting film 2 of thesemiconductor element 1 and the sealing member 6 of the device.

(1) Production of semiconductor device

A polyimide precursor composition, which was an Nmethyl-2-pyrrolidonesolution (solid content=25% by weight) of compound 1 [a polyimideprecursor having a recurring unit constitution represented by chemicalformula (10)] synthesized in Synthesis Example 1, was spin-coated on asilicon wafer in which semiconductor element regions and wiring layershad been formed. The coated composition was dried at 90° C. for 4minutes and then at 100° C. for 4 minutes by the use of a hot place toobtain a polyimide precursor film having a thickness of 18 μm. The filmwas cured at 200° C. for 30 minutes and then at 350° C. for 30 minutesto obtain a polyimide film having a thickness of 10 μm.

The portions of the polyimide film corresponding to the bonding padareas and to-be-scribed regions of the silicon wafer were removed byphotoetching using a cyclized polyisoprene-based photoresist and ahydrazine-based etchant for polyimide. Then, the remaining photoresistwas removed to obtain a surface-protecting film made of a polyimide.

Thus, a silicon wafer 9 having a surface-protecting film 2, shown inFIG. 2A was obtained. In this silicon wafer 9, the bonding pad areas 7and the to-be-scribed regions 8 are exposed. The silicon wafer 9 was cutat the to-be-scribed regions 8 to obtain a semiconductor element 1having a surface-protecting film 2, shown in FIG. 2B.

Then, as shown in FIG. 2C, there was prepared an adhesive member 4 madeof a polyimide film having a polyamide imide ether layer on either ofthe front or back side. External terminals (lead frames) 3 were providedon the side of the adhesive member 4 having no polyamide imide etherlayer; the semiconductor element 1 was provided on the side of theadhesive member 4 having a polyamide imide ether layer so that thesurface-protecting film 2 and the polyamide imide ether layer faced eachother; and they were press-bonded at 400° C.

Thereafter, as shown in FIG. 2D, the bonding pad areas 7 and theexternal terminals 3 were connected with a gold wire 5 by the use of awire bonder. As shown in FIG. 2E, molding was conducted with asilica-containing epoxy sealant at a temperature of 180° C. at apressure of 70 kg/cm² to form a sealing member 6. Lastly, the externalterminals 3 were bent in a desired shape to obtain a DRAM product shownin FIG. 2F or FIG. 1.

(2) Evaluation of peeling resistance

The DRAM obtained in the present Example has, as a surface-protectingfilm for semiconductor element, a polyimide film obtained by heat-curinga polyimide precursor composition containing compound 1 (a polyimideprecursor).

The DRAM was allowed to stand under the constant-temperature andconstant-humidity conditions of 85° C. and 85% for 200 hours; then,heated at 260° C. for 10 seconds (solder reflowing conditions); andsubjected to ultrasonic search to examine the occurrence ornon-occurrence of peeling. There was no peeling between thesurface-protecting film 2 and the sealing member 6, and the DRAM was ahighly reliable semiconductor device.

COMPARATIVE EXAMPLE 5

The test results obtained using the technique described in JP-B-63-31939are shown for comparison.

(1) Preparation of polyimide precursor

100 g (0.5 mol) of 4,4′-diaminodiphenyl ether was dissolved, in anitrogen current, in 1,791 g of a 1:1 mixture of N-methyl-2-pyrrolidoneand N,N-dimethylacetamide to prepare an amine solution. The solution waskept at about 15° C. with ice-cooling. Thereto was added 109 g (0.5 mol)of pyromellitic acid dianhydride with stirring. After the addition, afurther reaction was allowed to occur for 5 hours at 15° C. Viscosityadjustment was made at 25° C. to obtain a polyamic acid solution havinga viscosity of 20 poises at 25° C.

(2) Production of semiconductor device

The above solution was spin-coated on a silicon wafer in whichsemiconductor element regions and wiring layers had been formed. Thecoated solution was dried at 90° C. for 4 minutes and then at 100° C.for 4 minutes by the use of a hot place to obtain a polyimide precursorfilm having a thickness of 18 μm. The film was cured at 200° C. for 30minutes and then at 350° C. for 30 minutes to obtain a polyimide filmhaving a thickness of 10 μm. The portions of the polyimide filmcorresponding to the bonding pad areas and to-be-scribed regions of thesilicon wafer were removed in the same manner as in Example 7. Theresulting material was subjected to the same procedure as in Example 7to produce a semiconductor device (a DRAM).

(3) Evaluation of peeling resistance

The DRAM was evaluated for peeling resistance during solder reflowing.The DRAM was allowed to stand under the constant-temperature andconstant-humidity conditions of 85° C. and 85% for 200 hours; then,heated at 260° C. for 10 seconds (solder reflowing conditions); andsubjected to ultrasonic search to examine the occurrence ornon-occurrence of peeling. There was peeling between the polyimide filmand the sealing resin.

EXAMPLES 8-13

Six DRAMs were produced in the same manner as in Example 1 except thatthe compound 1 used in Example 1 was replaced by compound 6 [a polyimideprecursor having a recurring unit constitution represented by chemicalformula (13)] synthesized in Synthesis Example 2, in Example 8; compound10 [a polyimide precursor having a recurring unit constitutionrepresented by chemical formula (16)] synthesized in Synthesis Example3, in Example 9; compound 14 [a polyimide precursor having a recurringunit constitution represented by chemical formula (19)] synthesized inSynthesis Example 4, in Example 10; compound 15 [a polyimide precursorhaving a recurring unit constitution represented by chemical formula(20)] synthesized in Synthesis Example 5, in Example 11; compound 16 [apolyimide precursor having a recurring unit constitution represented bychemical formula (21)] synthesized in Synthesis Example 6, in Example12; and compound 17 [a polyimide precursor having a recurring unitconstitution represented by chemical formula (22)] synthesized inSynthesis Example 7, in Example 13.

Each of the DRAMs obtained in the present Examples 8-13 has, as asurface-protecting film for semiconductor element, a polyimide filmobtained by heat-curing a polyimide precursor composition containingcompound 6, 10, 14, 15, 16 or 17.

Each DRAM was allowed to stand under the constant-temperature andconstant-humidity conditions of 85° C. and 85% for 200 hours; then,heated at 260° C. for 10 seconds (solder reflowing conditions); andsubjected to ultrasonic search to examine the occurrence ornon-occurrence of peeling. In each DRAM, there was no peeling betweenthe surface-protecting film 2 and the sealing member 6, and each DRAMwas a highly reliable semiconductor device.

EXAMPLE 14

A semiconductor device was produced using a polyimide precursorcomposition which contained compound 21 and which further contained aphotosensitizer for photosensitivity. The device was examined forpeeling resistance.

(1) Production of semiconductor device

A solution (solid content=25% by weight) of 100 parts by weight ofcompound 21 [a polyimide precursor having a recurring unit constitutionrepresented by chemical formula (29)] synthesized in Synthesis Example8, dissolved in a 8:2 mixture of N-methyl-2-pyrrolidone and xylene wasmixed with 31.4 parts by weight of 2-(N,N-dimethylamino)ethylmethacrylate, 2.0 parts by weight of Michler's ketone and 2.0 parts byweight of 1,3-diphenyl-1,2,3-propanetrione-2-(o-ethoxycarbonyl) oxime,whereby a polyimide precursor composition was obtained. The compositionwas spin-coated on a silicon wafer in which semiconductor elementregions and wiring layers had been formed. The coated composition wasdried at 90° C. for 4 minutes and then at 100° C. for 4 minutes by theuse of a hot plate to obtain a photosensitive film having a thickness of18 μm.

The film was irradiated with ultraviolet rays for 20 seconds through agiven photomask by the use of an i-line stepper. The irradiated film wassubjected to development with a developer consisting of 4 volumes ofN-methyl-2-pyrrolidone and 1 volume of water, followed by rinsing withisopropyl alcohol, whereby the non-irradiated portions of thephotosensitive film corresponding to the bonding pad areas andto-be-scribed regions of the silicon wafer were removed to obtain apolyimide precursor film of desired pattern. The film was cured at 200°C. for 30 minutes and then at 350° C. for 30 minutes to obtain asurface-protecting film of desired pattern, made of a polyimide. Thefilm had a thickness of 10 μm.

The thus-obtained silicon wafer having a surface-protecting film was cutat the to-be-scribed regions to obtain a semiconductor element having asurface-protecting film. To this semiconductor element was adheredexternal terminals via an adhesive member; the bonding pad areas of thesemiconductor element and the external terminals were connected with agold wire; molding was conducted with a silica-containing epoxy sealantat a temperature of 180° C. at a pressure of 70 kg/cm²; and the externalterminals were bent in a desired shape to obtain a DRAM product.

(2) Evaluation of peeling resistance

The DRAM obtained in the present Example has, as a surface-protectingfilm for semiconductor element, a polyimide film formed by heat-curing apolyimide precursor composition containing 100 parts by weight ofcompound 21, 31.4 parts by weight of 2-(N,N-dimethylamino)ethylmethacrylate (an amine compound having a carbon-to-carbon double bond),2.0 parts by weight of Michler's ketone (a photosensitizing agent) and2.0 parts by weight of1,3-diphenyl-1,2,3-propanetrione-2-(o-ethoxycarbonyl) oxime (aphotosensitizing aid).

The DRAM was allowed to stand under the constant-temperature andconstant-humidity conditions of 85° C. and 85% for 200 hours; then,heated at 260° C. for 10 seconds (solder reflowing conditions); andsubjected to ultrasonic search to examine the occurrence ornon-occurrence of peeling. There was no peeling between thesurface-protecting film 2 and the sealing member 6, and the DRAM was ahighly reliable semiconductor device.

EXAMPLES 15-20

Six DRAMs were produced in the same manner as in Example 14 except thatthe compound 21 used in Example 14 was replaced by compound 22 [apolyimide precursor having a recurring unit constitution represented bychemical formula (30)] synthesized in Synthesis Example 9, in Example15; compound 23 [a polyimide precursor having a recurring unitconstitution represented by chemical formula (31)] synthesized inSynthesis Example 10, in Example 16; compound 24 [a polyimide precursorhaving a recurring unit constitution represented by chemical formula(32)] synthesized in Synthesis Example 11, in Example 17; compound 25 [apolyimide precursor having a recurring unit constitution represented bychemical formula (33)] synthesized in Synthesis Example 12, in Example18; compound 26 [a polyimide precursor having a recurring unitconstitution represented by chemical formula (34)] synthesized inSynthesis Example 13, in Example 19; and compound 27 [a polyimideprecursor having a recurring unit constitution represented by chemicalformula (35)] synthesized in Synthesis Example 14, in Example 20.

Each of the DRAMs obtained in the present Examples 15-20 has, as asurface-protecting film for semiconductor element, a polyimide filmobtained by heat-curing a polyimide precursor composition containingcompound 22, 23, 24, 25,26 or 27, an amine compound having acarbon-to-carbon double bond, a photosensitizing agent and aphotosensitizing aid.

Each DRAM was allowed to stand under the constant-temperature andconstant-humidity conditions of 85° C. and 85% for 200 hours; then,heated at 260° C. for 10 seconds (solder reflowing conditions); andsubjected to ultrasonic search to examine the occurrence ornon-occurrence of peeling. In each DRAM, there was no peeling betweenthe surface-protecting film and the sealing member, and each DRAM was ahighly reliable semiconductor device.

EXAMPLE 21

A solution (solid content=25% by weight) of 100 parts by weight ofcompound 28 [a polyimide precursor having a recurring unit constitutionrepresented by chemical formula (36)] synthesized in Synthesis Example15, dissolved in a 8:2 mixture of N-methyl-2-pyrrolidone and xylene wasmixed with 31.4 parts by weight of 2-(N,N-dimethylamino)ethylmethacrylate and 7.2 parts by weight of2,6-di(4′-azidobenzal)-hydroxycyclohexanone, whereby a polyimideprecursor composition was obtained. Using this composition, a DRAM wasproduced in the same manner as in Example 14.

The DRAM obtained in the present Example has, as a surface-protectingfilm for semiconductor element, a polyimide film formed by heat-curing apolyimide precursor composition containing 100 parts by weight ofcompound 28, 31.4 parts by weight of 2-(N,N-dimethylamino)ethylmethacrylate (an amine compound having a carbon-to-carbon double bond)and 7.2 parts by weight of 2,6-di(4′-azidobenzal)-hydroxycyclohexanone(a photosensitizing agent).

The DRAM was allowed to stand under the constant-temperature andconstant-humidity conditions of 85° C. and 85% for 200 hours; then,heated at 260° C. for 10 seconds (solder reflowing conditions); andsubjected to ultrasonic search to examine the occurrence ornon-occurrence of peeling. There was no peeling between thesurface-protecting film and the sealing member, and the DRAM was ahighly reliable semiconductor device.

EXAMPLES 22-27

Six DRAMs were produced in the same manner as in Example 21 except thatthe compound 28 used in Example 21 was replaced by compound 29 [apolyimide precursor having a recurring unit constitution represented bychemical formula (37)] synthesized in Synthesis Example 16, in Example22; compound 30 [a polyimide precursor having a recurring unitconstitution represented by chemical formula (38)] synthesized inSynthesis Example 17, in Example 23; compound 31 [a polyimide precursorhaving a recurring unit constitution represented by chemical formula(39)] synthesized in Synthesis Example 18, in Example 24; compound 32 [apolyimide precursor having a recurring unit constitution represented bychemical formula (40)] synthesized in Synthesis Example 19, in Example25; compound 33 [a polyimide precursor having a recurring unitconstitution represented by chemical formula (41)] synthesized inSynthesis Example 20, in Example 26; and compound 34 [a polyimideprecursor having a recurring unit constitution represented by chemicalformula (42)] synthesized in Synthesis Example 21, in Example 27.

Each of the DRAMs obtained in the present Examples 22-27 has, as asurface-protecting film for semiconductor element, a polyimide filmobtained by heat-curing a polyimide precursor composition containingcompound 28, 29, 30, 31, 32 or 33, an amine compound having acarbon-to-carbon double bond and a photosensitizing agent.

Each DRAM was allowed to stand under the constant-temperature andconstant-humidity conditions of 85° C. and 85% for 200 hours; then,heated at 260° C. for 10 seconds (solder reflowing conditions); andsubjected to ultrasonic search to examine the occurrence ornon-occurrence of peeling. In each DRAM, there was no peeling betweenthe surface-protecting film and the sealing member, and each DRAM was ahighly reliable semiconductor device.

EXAMPLE 28

A polyimide precursor was obtained as a polyimide precursor compositionof solution form (solid content=25% by weight) containing a polyimideprecursor represented by chemical formula (43), in the same manner as inSynthesis Example 22.

The polyimide precursor composition (solution) was spin-coated on asilicon wafer in which semi-conductor element regions and wiring layershad been formed. The coated composition was dried at 90° C. for 4minutes and then at 100° C. for 4 minutes to obtain a film having athickness of 18 μm. The film was cured at 200° C. for 30 minutes andthen at 350° C. for 30 minutes to obtain a polyimide film having athickness of 10 μm. The polyimide film was subjected to photoetchingusing a cyclized polyisoprene-based photoresist and a hydrazine-basedetchant for polyimide, to remove the portions of the polyimide filmcorresponding to the bonding pad areas and to-be-scribed regions of thesilicon wafer. Then, the remaining photoresist was removed to obtain awafer having a polyimide film (a surface-protecting film) at the surfaceportions other than the bonding pad areas and to-be-scribed regions. Thewafer obtained above was cut at the to-be-scribed regions to separateindividual chips.

There was prepared, as an adhesive member, a polyamide film having apolyamide imide ether layer (an adhesive) on one side. On the side ofthe adhesive member having no polyamide imide ether layer were providedexternal terminals; on the side of the adhesive member having apolyamide imide ether layer was provided the above-obtained chip so thatthe polyamide imide ether layer and the surface-protecting film of thechip faced each other; and they were press-bonded at 400° C. Then, thebonding pad areas of the chip and the external terminals were connectedwith a gold wire by the use of a wire bonder. Thereafter, molding wasconducted by the use of a silica-containing epoxy sealant at atemperature of 180° C. at a pressure of 70 kg/cm² to form a resin-madesealing member. Lastly, the external terminals were bent in a desiredshape to obtain a product of DRAM.

The DRAM was kept for 200 hours in an atmosphere of 85° C. (temperature)and 85% (relative humidity), then heated at 260° C. for 10 seconds(solder reflowing conditions), and subjected to ultrasonic search toexamine the occurrence or nonoccurrence of peeling. There was no peelingbetween the polyimide film and the sealing resin, and the DRAM was ahighly reliable product. In order to examine the heat resistance ofpolyimide, a polyimide film having a thickness of 10 μm was preparedseparately and measured for weight decrease-starting temperature. Thepolyimide film had a satisfactory weight decrease-starting temperatureof 400° C. Incidentally, weight decrease-starting temperature ofpolyimide film must be at least 380° C. in order for the polyimide filmto have sufficient practical applicability.

Japanese Patent Application No. 6-207306 is hereby incorporated in itsentirety by reference.

While the present invention has been described in some detail forpurposes of clarity and understanding, it will be appreciated by thoseskilled in the art from a reading of the disclosure that various changesin form and detail can be made without departing from the true scope ofthe present invention and appended claims.

What is claimed is:
 1. A process for producing a resin-sealedsemiconductor device, which comprises a protecting film formation stepof forming, on at least part of the surface of a semiconductor element,a surface-protecting film by coating thereon a polyimide precursorcomposition containing a polyimide precursor having a recurring unitconstitution represented by the following general formula (1) andheat-curing the coated polyimide precursor composition:

wherein R¹ is a trivalent or tetravalent aromatic group; R² and R³ areeach a tetravalent organic group having 4 or more carbon atoms; R⁴ is abivalent organic group having 4 or more carbon atoms; X is a bivalentorganic group containing at least one member selected from the groupconsisting of oxygen and nitrogen: Y is a monovalent organic grouphaving 15 or less carbon atoms; n=5-100 and m=0-95 with a proviso thatn+m=100; and p is 1 or 2, a semiconductor element-mounting step ofmounting the above-obtained semiconductor element having the protectingfilm, on external terminals, and a sealing step of sealing thesemiconductor element mounted on the external terminals, with a resin.2. A process according to claim 1, wherein the protecting film formationstep comprises a sub-step of forming said protecting film on at leastpart of the front or back side of a silicon wafer containing at leastone semiconductor element region and to-be-scribed regions isolatingeach semiconductor element region, and a sub-step of cutting the siliconwafer at the to-be-scribed regions to separate each semiconductorelement region to form each semiconductor element having a protectingfilm.
 3. A process according to claim 1, wherein the polyimide precursorcomposition contains 100 parts by weight of said polyimide precursor,1-400 parts by weight of an amine compound having a carbon-to-carbondouble bond, and 0.1-30 parts by weight of a photosensitizer.
 4. Aprocess according to claim 1, wherein the polyimide precursor has arecurring unit constitution represented by the following general formula(8):

wherein R² and R³ are each an tetravalent organic group having 4 or morecarbon atoms; R⁴ is a bivalent organic group having 4 or more carbonatoms; R⁶ is a phenyl group or an alkyl group having 4 or less carbonatoms; X is a bivalent organic group selected from the group consistingof —COO—, —NHCOO— and —NHCONH—; k is an integer of 2-4; and n=5-100 andm=0-95 with a proviso that n+m=100.